ATLANTA - Georgia environmental regulators, frequently criticized as lax on air and water pollution, are about to clamp down on mercury emissions from coal burning power plants.

A state Board of Natural Resources committee Tuesday unanimously approved limits on mercury that would be among the toughest in the Southeast. The full board is expected to go along with the proposal today.

The new rule would require Georgia Power Co. to install state-of-the-art pollution control equipment at most of the 10 coal burning plants the utility operates across Georgia.

The upgrades are expected to cut emissions of mercury by 75 percent to 85 percent by 2015, Heather Abrams, chief of the state Environmental Protection Division's Air Protection Branch, told members of the board's Environmental Protection Committee.

Abrams said the new equipment also will reduce emissions of nitrogen oxide and sulfur dioxide, which contribute to summer smog and fine particle-pollution, respectively. Nitrogen oxide emissions are expected to be cut in half, while sulfur dioxide will be reduced by 90 percent, she said.

"It's a really big deal that this is going in place," she said.

Coal fired power plants are the chief source of man-made mercury in Georgia. Mercury spewed into the air from the plants' smokestacks gets into the water and, thus, into fish.

In some parts of the state, mercury contamination has resulted in advisories warning consumers - especially pregnant and nursing women and young children - not to eat fish caught in local waters more than once a month.

The new mercury rule has divided the state's environmental advocates. Some groups have endorsed the proposal as a long overdue crackdown on Georgia Power, which plans to spend about $4 billion complying with the rule.

But others aren't satisfied.

"We want to be able to eat all the fish we legally catch from all waters at all times," Chandra Brown, executive director of Ogeechee-Canoochee Riverkeeper, said Tuesday. "Nothing less is acceptable."

Brown objected to an exemption in the rule for several of the smallest coal burning plants operated by Georgia Power, including facilities in Albany and Savannah.

All of those plants are located near black water rivers in South Georgia, which are particularly vulnerable to mercury contamination.

But committee Chairman Tom Wheeler said Georgia Power is showing a strong commitment to cooperating with the state by making such a large investment to meet the new standards.

"This is certainly a great improvement over what we have now," he said.